This invention relates to improved apparatus and methods for the treatment of prostate cancer. More particularly, the present invention provides a prostate visualization device comprising a bladder neck balloon, and methods of use.
Excluding nonmelanoma skin cancers, prostate cancer is the most common cancer afflicting American men. The American Cancer Society estimates that over 180,00 new cases will be diagnosed in the U.S. in the year 2000 alone, and that nearly 32,000 people will die from the disease. Prostate cancer is second only to lung cancer as the leading cause of cancer death in men, accounting for roughly 11%.
Prostate cancer is defined as malignant tumor growth within the prostate gland. Its cause is unknown, although high dietary fat intake and increased testosterone levels are believed to be contributory factors. A letter scale (xe2x80x9cAxe2x80x9d through xe2x80x9cDxe2x80x9d), which accounts for the location of the cancer, is commonly used to classify the stage of disease. In Stage A, the tumor is not palpable but is detectable in microscopic biopsy. Stage B is characterized by a palpable tumor confined to the prostate. By Stage C, the tumor extends locally beyond the prostate with no distant metastasis. By Stage D, cancer has spread to the regional lymph nodes or has produced distant metastasis.
In the early stages, prostate cancer is most commonly treated by either prostate removal or by brachytherapy. More advanced cases are treated by hormonal manipulation or orchiectomy to reduce testosterone levels and curb spreading of the disease, by chemotherapy, or by external beam radiation therapy.
With regard to treatment of early stage prostate cancer, the state of the art has several drawbacks. Radical prostatectomy is often recommended for treatment of localized stage A and B prostate cancers. Under general or spinal anesthesia, an incision is made through a patient""s abdomen or perineal area, and the diseased prostate is removed. The procedure is lengthy, especially if a lymph node dissection is simultaneously performed, and requires a hospital stay of 2-5 days. Possible complications include impotence and urinary incontinence.
Internal radiation therapy or brachytherapy has recently been developed and holds great promise for the treatment of early stage prostate cancer. Radioactive pellets or seeds of, for example, iodine-125, palladium-103, or iridium-192, are deposited directly into the prostate through needle placement. U.S. Pat. No. 5,928,130 to Schmidt provides a slightly modified example of such a needle device. Imaging techniques, such as transrectal ultrasound, CT scans, or MRI, are used to accurately guide placement of the radioactive material. Advantageously, radiation from the brachytherapy seeds is administered directly to the prostate with less damage to surrounding tissues, delivering a substantially higher radiation dosage to the prostate than to the surrounding tissues, as compared to external beam radiation therapy. The procedure need only be performed once, and impotence and urinary incontinence complications are significantly reduced, as compared to prostate removal procedures.
The seeds, which are permanently implanted, give off radiation for weeks or months. Their presence causes little discomfort, and they remain in the prostate after decay of the radioactivity. For several weeks following needle insertion, patients may experience pain in the perineal area, and urine may have a red-brown discoloration.
Although, when performed correctly, brachytherapy may provide several benefits when compared to prostate removal and other techniques, current surgical apparatus and methods for delivering the seeds to target locations within the prostate are somewhat crude and are subject to practitioner error. The current method of identifying the depth of needle insertion is by ultrasound imaging. The junction of the base of the prostate and the bladder provides a common reference plane for needle insertion. Identifying this critical reference xe2x80x9cbasexe2x80x9d plane is critical to proper needle and seed placement.
A present technique for imaging the base plane is to visualize the plane in either transverse or sagittal ultrasound imaging. Injection of contrast agent may facilitate imaging. A catheter, such as a standard Foley catheter, may be inserted into the patient""s urethra proximal of the junction. Contrast agent comprising aerated K-Y jelly and water, may then be injected through an end port of the catheter. The agent moves distally towards the patient""s bladder and is visible to an ultrasound probe, positioned in the patient""s rectum, thereby facilitating imaging.
Attempts have been made to improve Foley catheters, as well as to facilitate improved imaging within a body lumen. For example, U.S. Pat. No. 5,715,825 to Crowley provides an acoustic imaging catheter with an inflatable dilation balloon and an ultrasound transducer. However, while Crowley may provide improved imaging, the device is mechanically and electrically complex, and is therefore subject to failure. U.S. Pat. No. 5,916,153 to Rhea, Jr. provides a multifunction, modified Foley catheter. The device described in that patent, however, does nothing to improve on current junction imaging techniques.
Progress has been made in the field of vascular wound closure in creating devices that conform to the shape of a vascular puncture to facilitate sealing of the puncture. For example, U.S. Pat. No. 5,868,778 to Gershony et al. provides a vascular sealing device with a balloon positioned at an end region. The device is inserted through a vascular puncture, the balloon is inflated, and the device is retracted until the balloon seals against the puncture.
In view of the drawbacks associated with previously-known methods and apparatus for bladder/prostate junction imaging, it would be desirable to provide methods and apparatus that overcome such drawbacks.
It further would be desirable to provide methods and apparatus that provide uniform and reliable imaging of the junction.
It still further would be desirable to provide methods and apparatus that may be used in conjunction with standard brachytherapy apparatus.
In view of the foregoing, it is an object of the present invention to provide methods and apparatus for bladder/prostate junction imaging that overcome drawbacks associated with previously-known methods and apparatus.
It is also an object of the present invention to provide methods and apparatus that provide uniform and reliable imaging of the bladder/prostate junction.
It still further is an object to provide methods and apparatus that may be used in conjunction with standard brachytherapy apparatus.
These and other objects of the present invention are accomplished by providing methods and apparatus for bladder/prostate junction imaging comprising a bladder neck balloon that sealing engages and defines an enclosed space within a proximal region of the bladder. The balloon may, for example, be shaped such that it conforms to the proximal region when inflated, or it may comprise regions of reduced elasticity such that it expands nonuniformly into the required shape. Echo-contrast agent may be injected into the enclosed space with uniform density, to facilitate reliable imaging with an ultrasound probe. Alternatively, the bladder neck balloon may be fabricated from a material that is opaque to ultrasound, thereby negating the need for contrast agent.
In a preferred embodiment, the balloon is coupled to a multi-lumen catheter. The lumens include an inflation lumen, a bladder drainage lumen, a contrast lumen, and a prostatic therapy lumen. The catheter is advanced through a patient""s urethra into the patient""s bladder. The balloon is inflated via the inflation lumen, and the catheter is proximally retracted until the balloon sealingly engages the proximal region and defines the enclosed space. Echo-contrast agent is injected into the space through the contrast lumen, such that it fills the space. Ultrasonic imaging may then proceed, often with an ultrasound probe positioned in the patient""s rectum. Urine may also be emptied from the bladder via the bladder drainage lumen, and the patient""s prostate may be accessed via the prostatic therapy lumen.
In an alternative embodiment with a radiopaque balloon, the catheter optionally may be provided without the contrast lumen. With the balloon sealingly engaging the proximal region and defining the enclosed space, ultrasonic imaging proceeds.
The bladder neck balloon may comprise a variety of shapes to facilitate imaging of bladders of different shapes and sizes. Shapes suited to specific patient populations will be apparent to those of skill in the art, and fall within the scope of the present invention.
Methods of using the present invention are also provided.